The early transcriptional responses in rose induced by Bacillus velezensis CLA178 and Agrobacterium tumefaciens C58

Abstract

AbstractBoth pathogens and beneficial microbes can induce plant defence responses. However, the defence responses to pathogenic Agrobacterium in Rose genus plants and the gene regulatory pathways induced by plant growth‐promoting rhizobacteria (PGPR) to resist pathogenic Agrobacterium are not clear. In this study, the growth of rose plants was inhibited by Agrobacterium tumefaciens C58 but promoted by a beneficial rhizobacterium, Bacillus velezensis CLA178. CLA178 also helped rose plants against crown gall disease. To investigate the early response of rose to pathogenic Agrobacterium and PGPR Bacillus, we performed RNA‐seq of rose cells in response to A. tumefaciens C58 and B. velezensis CLA178. The overall transcriptional changes in response to C58 were weaker than those to CLA178, and 93.08% of the transcriptional changes in rose induced by C58 overlapped with the CLA178 profile. Reactive oxygen species (ROS) accumulated in rose cells inoculated with CLA178 but not in those inoculated with C58. The suppression of rose plant defence responses to the pathogen C58 favours its infection. We found that CLA178 triggers rose plant defences by inducing oxidative burst and upregulating the expression of genes related to the stress response and plant–pathogen interactions. In addition, we found that the expression of histone gene families that assist T‐DNA integration into the host genome was decreased by CLA178. The upregulated expression of NRT2.4, LRX6 and CAD1 by CLA178 might contribute to the plant growth promotion by CLA178. The study provides insight into the response of woody plant rose to pathogenic Agrobacterium and a potential mechanism induced by CLA178 against crown gall disease in rose.